Specifically, lawmakers are asking Trump to appeal to Attorney General Jeff Sessions, who on Jan. 4 rescinded the Cole Memo—an Obama-era policy that left the enforcement of cannabis up to individual states and not the federal government.

Oregon is one of nine states to have passed laws legalizing the recreational use of marijuana. Dozens of other states have passed similar laws de-criminalizing the medical use of cannabis.

Today's letter is a plea to Trump to protect the jobs, small businesses and state infrastructure created by the still-young cannabis industry.

The authors of the letter also point out that enforcing legal marijuana transactions protects consumers from black market sales.

"New policies have helped eliminate the black market sale of marijuana and allowed law enforcement to focus on real threats to public health and safety," the letter to Trump reads.

"This action by the Department of Justice has the potential to unravel efforts to build sensible drug policies that encourage economic development as we finally move away from antiquated practices that have hurt disadvantaged communities."

Signatories also point to Trump's statement as a candidate that he would "leave [marijuana] up to the states."

"We trust you still hold this belief," the letter says, "and we request that you urge the Attorney General to reinstate the Cole Memo."